Shoe stiffener material and art of making



atented Aug. 18, 1931 PATIENT? OFFICE FRANK O. WOODRUFF, OF QUINCY, MASSACHUSETTS, ASSIGNOR TO BECKWITH MANU- FACTURING COMPANY, 013' BOSTON, MASSACHUSETTS, A CORPORATION OF 'MASSA- 2N0 Drawing.

This invention relates to the production of sheet material intended more particularly for use in making shoe stifi'ener's such as counters or box toes. Such sheet material usually comprises a fibrous base, such as felt, saturated with an agent which under sultable treatment quickly becomes plastic or gelatinous but which quickly sets or hardens under atmospheric temperature conditions. 19 The sheet material is cut into stifi'ener blanks, which when subjected to treatment designed to plasticize or gelatinize the agent present therein becomes soft and limp, in which condition the blanks are moulded or shaped to the desired form and'permitted to set in such form. Various classes of agents may be used to impart the desired stiffness or rigidity to the moulded article, but cellulose derivatives such as the nitrate and acetate have 20 sometimes been preferred, not only because of the rapidity with which they undergo gelatinization when treated with suitable solvents, but also because they set rapidly under room temperature conditions as the solvent is evaporated to produce a product characterized by itsstifi'ness, resiliency, and perma-' nency against varying atmospheric temperature conditions.

An object of the present invention is to provide a shoe stiffener material in which a cellulose derivative capableof being gelatinized by a volatile solvent is uniformly distributed in such condition as to make possible a rapid, uniform, and substantially complete gelatinization by the solvent. In accordance with the present invention, this object is attained by coating suitable papermaking fibrous material with a solution of the cellulose derivative, then beating the coated fibrous material 4.0 to a'pulpousconditionsuitable for forming into paper, and forming the beaten stock into a waterlaid felt on a paper machine. After the coating of the fibrous material and before introducing it into the beater engine,

be evaporated and recovered, in which case the derivative is deposited on and adheresto the fibers in a set condition and commingling of the solvent with the water used in the beater engine in preparing the pulp is the solvent .of the cellulose derivative may SHOE STIFFENEB MATERIAL AND ART OF MAKING- A-ppl ication filed January 18, 1930. Serial No. 421,814.

avoided. The fibrous material to be coated with the solution of the derivative may be in a loose, unwoven condition so that it may be admixed with the solution, or it ma be in the form of a woven or knitted fabr1c so that it may be'impregnated or coated on one or both faces with the solution. A straight solution of only the derivative may be employed, but, if desired, agents less expensive than the derivative, such as rosin, may be added in suitable proportion to the solution to increase the amount of solid material deposited upon the fibrous material upon removal of the solvent, but Without materially interfering with the capacity of thevderivative for undergoing gelatinizationby the action of a solvent. When nitrocellulose is the derivative, it ma be com ounded with camphor as celluloid. When t e fibrous material, more or less coated with cellulose derivative, is beaten and run out into a waterlaid sheet on suitable papermaking machinery, e. g., a wet machine, and then dried, it is found thatthe product is of high porosity and is not unlike ordinary paper in its flexibility, feel, and other characteristics. Such sheet material lends itself with especial facility to the operations of cuttin into shoe stiffener blanks and to skiving o the blanks at their marginal portions. The blanks may be rapidly and unlformly impregnated with a solvent for the derivative, as by dipping thereinto, to effect a rapid and complete gelatinization of the cellulose derivative present therein. A blank thus treated becomes sufliciently soft or limp to be easily formed ormoulded to the shape of the last used in making the shoe, and upon the eva oration of the solvent becomes set in a sti condition, in which; condition it is practically and resilient unaffected even by extreme atmospheric tem perature conditions. 1

One of the major advantages of a process such as described is that practically all the cellulose derivative used as a rawmaterial appears in the finishedwaterlaid sheet of fibers. Evidently the cellulose derivative initially deposited on and adherent to the fiber remains fixed to the fibers throughout beating and papermaking operations, as evipaper pulp in the beater engine, and then to run out the stock on a paper machine. Such a process, however, is commercially unfeasible, not only because ofthe expense incident to the step of pulverization, but more particularly because of the material loss of celluloid in the white water removed during formation of the paper.

Another important advantage possessed by my process is that it makes possible the use of celluloid-coated fabric clippingsor other waste fibrous material associated with cellulose derivatives or compounded derivatives, as a raw material. "For instance, one available source of waste is the cuttings producd whenmaking -shoe stilfeners by impregnating or coating a fabric on one.or both sides with a compounded cellulose derivative, such as celluloid, and then cutting into the stiffeners. Such waste material may comprise a high grade cotton fiber, which may be beaten and formed. into a "sheet having excellent characteristics. Another available source "of wasteis the paper cuttings produced when making shoe stifi'eners in accordance with the present invention.

The gelatinization of the cellulose derivative prior to the coating of the fibrous material may be accomplished by theuse of suitable solvents for the derivative, whereupon after coatlng of the fibrous material has been effected, the solvent may be vaporized, under solution. To the dissolved acetate is gra ual- 1y added, with stirring, 100 parts of cellulosic fiber, such as cotton. For this pur ose, a mixing and kneading machine, suc as a Werner and Pfleiderer, or dough-kneading machine, is preferably, though not necessarily employed. The viscosity of the solution is so increased by the addition of the fiber that when all the fiber has been incorporated thereinto, a mass of spreadableconsistency is obtained. The mass is then spread out by any suitable mechanical means, and permitted to dry, as a result of which is 13 found that setting into a hard, coherent sheet has taken place. The sheet is then cut into small pieces and addedto a beater engine together with suflicient water to ensure circulation. The beater'is initially operated for about an hour with the roll raised sufiiciently so that the pieces undergo a combin' or teas-' ing operation, which liberates the fi ers carryin cellulose acetate attached thereto, in -the orm of a pulp. The beater roll is then gradually lowered, so that at the end of 7 about one hour it is in sufiiciently close proximity with the bed-plate to effect a brushing of the fibers, whereupon beating is continued until thestock is in a condition suitable for forming into a sheet. The stock is thenv charged into the vat of a papermaking machine and run off into a waterlaid sheet of, say, about 50 points thickness. The sheet is then dried and cut into stiffener blanks, which are preferably skived at their marginal portions. If desired, fabric such as cheeseclothmay be adhesively secured to elevated temperature conditions and while) ith or both faces of the sheet prior to cut effecting a recovery of the solvent, if desired. When loose, unwoven fiber in flufiy or bulk condrtlon 1s employed as a raw material, sufi'iclent solvent .is'preferably employed to produce a fairly thin solution, whereupon beris added to the solutiorr and uniformly dlstrlbuted therethrough' in order to effect a coating of substantially all the fibers with the cellulose derivative; and thereafter the solvent is permitted to evaporate. The dried product is disl tegrated into pieces of-convenient size and is beaten in the presence of water to form a pulp capable of being formed into waterlaid sheets of uniform texture on a paper machine. I R

A-specific example of procedure which g ves a highly satisfactory product is carr1ed out substantially as follows. One hun- "dred parts of cellulose acetate is dissolved in sufiicient methyl-cellosolve (a well known solvent mlxture) to produce a solutionof a;

tingi nto blanks so as to avoid undue tackiness on the surface of the blanks after gelat-' inization. of the cellulose derivative comonent by treatment with solvent. Box toe lanks, packaged and sold in dry condition, may be saturated with the solvent at the shoe factory immediately prior to pulling over or lasting; but it is generallypreferable to treat the blanks with the solvent at the shoe stiifener factory, and then to package the solvent-saturated stiffeners in hermetically sealed containers so that they will reach the shoe manufacturer in a lim condition ready for assembly with the s 0e upper. When the treatment of the blanks is effected at the point of use in the shoe factory, there may be insuflicient time for the solvent to penetrate uniformly throughout the fibrous structure and accordingly incomplete gelatinization of the cellulose derivative component may occur. When, however, the solventtreated blanks aresupplied to the shoe manution of the cellulose derivative component.

The prolonged contact of the solvent with the cellulose'fibers also appears to effect their softening. The blanks thus conditioned may accordingly be lasted with the shoe uppers more readily and satisfactorily.

The example hereinbefore given is merely illustrative, as it is possible to vary raw materials, proportions, and mode of treatment. Thus, the cellulose acetate employed as a raw material may be either chloroform-soluble or acetone-soluble, so that chloroform or acetone may be used in lieu of the methyl-cellosolve which is a solvent for both varieties of the acetate. Cellulose nitrate may be used instead of cellulose acetate, in which case methyl cellosolve or one of the usual nitrocellulose solvents may be employed; but cellulose acetate possesses the advantage over nitrocellulose, in that it is non-explosive and of comparatively low inflammability. Any suitable papermaking pulp may be used, including rag fibers, waste silk, and chemical wood pulps, such as kraft and sulphite pulp, but long-fibered stocks, such as cotton, manila, hemp, jute, ramie, are preferable, in that they afford a finished sheet of high tear resistance. Mixtures of long and short fibers maybe used. or the fiber may be in the form of a woven or knitted fabric or of apaper or felt, in which case such a base or foundation is impregnated or coated on one or both faces with the solution of cellulose derivative, and, after cutting into pieces of a size capable of being operated upon by the beater engine, is introduced into the engine and reduced to a pulp according to the desired beating schedule. The fiber surfaces of the foundation may be partially or completely coated with films of derivative after the treatment with the solution of derivative, but during the beating operation, fresh, uncoated fiber surfaces may be exposed, so that when the stock is in condition for forming into the sheet, it is composed of individual fibers or fiber aggregates, which are spotted with or carry discontinuous coatings of cellulose derivative.

I am aware of the fact that it has been proposed tojncorporate cellulose derivatives, such as the nitrate and acetate, into felted fibrous foundations, as by dipping the prepared sheet material into a solution of such derivatives. Not only, however, is it difficult to efiect a uniform impregnation of the sheet with a large amount of derivative by such a process, but a substantial proportion of the interstices or voids of the sheet are filled because the cellulose derivative exists as a continuous phase, so that subsequent penetration by a solvent to effect gelatinization of the derivative is impeded. I am also aware of the fact that it has been proposed to incorporate cellulose derivatives, suchas the nitrocellulose, in fibrous condition into paper stock in the beater engine prior to its sheeting in fibrous condition. Because the.

fibers of cellulose derivatives are weak or tender, however, the resulting sheet is quite fragile, especially when a substantial proportion of such fibers are used in the stock. Moreover, beating generates pulverized derivative, which, being unattached to the fibers of the stock, tends to flow out along with the water in which it is suspended during paper formation.

I claim:

'1. Shoe stiffener material comprising a porous, waterlaid sheet of felted fibers to which is attached as a discontinuous phase a previously gelatinized cellulose derivative capable of again being gelatinized by a volatile solvent and of rendering said material stiff upon the evaporation of the solvent.

2. Shoe stiffener material comprising a porous, waterlaid sheet of felted cellulose fibers at leastpartially coated with a previously gelatinized cellulose derivative existing as a discontinuous phase and capable of again being gelatinized by a volatile solvent and of rendering said material stiff upon the evaporation of the solvent.

3. A box toe blank capable of being rendered limp by a cellulose acetate solvent and of setting in stiff condition, comprising a porous waterlaid sheet of felted cellulose fibers towhich is attached as a discontinuous phase previously gelatinized cellulose acetate.

4. A box toe blank comprising a porous waterlaid sheet of fibers at least partially coated with a previously gelatinized cellulose derivative existing as a discontinuous phase and capable of again being gelatinized by a volatile solvent and of rendering said blank stiff upon the evaporation of the solvent, said derivative being present in amount by weight approximately equal to that of the weight of the fiber. g

5. A process which comprises beating fibrous material coated with a previously gelatinized cellulose derivative capable of again being gelatinized by a volatile solvent, and sheeting the beaten stock on a paper machine.

6. A process which comprises gelatinizing a cellulose derivative with a volatile solvent, applying the gelatinized derivative to fibrous material, beating the fibrous material in the presence of water to form a pulp, and sheeting the pulp on a paper machine.

7. A process which comprises gelatinizing, a cellulose derivative with a volatile solvent, mixing loose cellulose fiber with the gelatinized derivative, beating the mixture in the presence of water to form a pulp,a'nd sheeting the pulp on a paper machine.

8. A process which comprises treating a cellulose derivative with suflicient volatile 5 solvent to form a thin solution, admixing cellulose fiber with the solution to produce a mass of spreadable consistency, evaporating the volatile solvent to effect a setting of the mass, beating the set productin water to form a pulp, and sheeting the pulp on a paper machine.

'9. A process which comprises treating a paper-making fibrous material with a gelatinized cellulose derivative capable of again being gelatinized by a volatile solvent, beating the treated fiber in the presence of water to form a pulp, sheeting the pulp on a paper machine, and cutting the sheet into shoe stifieners. 2 10. A process which comprises dissolving a cellulose derivative in a volatile solvent, coating a paper-making fibrous material substantially uniformly with the solution, evaporating the solvent, beating the material in the presence vof water to form a pulp, sheeting the pulp on a paper'machine, cutting the sheet into shoe stifi'eners, and treating the stiffeners with the volatile solvent to effeet a gelatinization of the cellulose derivative.

In testimony whereof I have afiixed my signature.

FRANK O. WOODRUFF. 

